In general, a semiconductor device may be processed in semiconductor technology, on and/or in a substrate (also referred to as a wafer or a carrier). The substrate may include a plurality of semiconductor devices, e.g. chips, which are processed or mounted in corresponding regions of the substrate. For fabricating such semiconductor devices, certain layers and layer stacks are formed, e.g. electrical interconnections, barriers, and active regions.
Conventionally, certain layer combinations and/or material combinations require a diffusion separation from each other, e.g. if they tend to react with each other. The diffusion separation may be provided by a barrier layer. However, during processing, higher temperatures may increase the reactivity and/or mobility of the atoms such that the barrier layer usually requires a high integrity to prevent diffusion between the respective layers. Defects in the barrier layer, which may arise during the processing, may impair the integrity of the barrier layer and may allow interdiffusion through the barrier layer, which may deteriorate the functionality of the layers, e.g. their capability for providing low resistance electrical connections, or may destroy the semiconductor device. By way of example, during forming the barrier layer, surface contaminations may induce holes in the barrier layer, illustratively acting as an interdiffusion gate. Further, a certain defect density of the barrier layers may decrease the reliability of the barrier layer with increasing interdiffusion area between the layers. By way of example, increasing the interface area between a contact pad and the active area may result in an increase of the failure rate of the produced semiconductor devices.
During processing of the semiconductor device and/or during reliability testing of the semiconductor device, a high temperature may be applied to the semiconductor device, e.g. greater than about 200° C., e.g. greater than about 400° C. This may increase a diffusion activity of material in the semiconductor device increasing a risk of destroying the semiconductor device during processing or testing.
Conventionally, the reliability of the barrier layer may be increased by increasing the number of barrier layers, e.g. by forming a barrier multilayer. Barrier multilayers require a higher effort, more process time, and additional material, which may increase production costs.
The reliability of a barrier multilayer may also decrease with increasing interdiffusion area. Further, defects arising from surface contaminations may extend through all layers of the barrier multilayers and, therefore, may not be reduced by increasing the number of barrier layers.